JP2003031916A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more easily provide a printed wiring board that can cope with miniaturization of electronic equipment and will not cause migration phenomenon. SOLUTION: A plurality of wiring patterns 5 is constituted of a conductive material containing highly conductive Ag powder, and at the same time, lead sections 6 for connection arranged by respectively connecting the sections 6 to the end sections of the patterns 5 are constituted of a conductive material, containing conductive particles obtained by coating the surfaces of conductive particles with Au layers. The lead sections 6 are arranged in parallel, at narrow intervals in the narrow insertion region 1c of a flexible insulating substrate 1, without coating the sections 6 with conductive films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board used for an operation panel of electronic equipment, and more particularly to a printed wiring board applicable to small electronic equipment.

[0002]

2. Description of the Related Art In a conventional printed wiring board, as shown in FIG. 8, a conductive pattern P1 is formed on a flexible insulating substrate 51, and the conductive pattern P1 includes a plurality of fixed contact portions 54 and respective fixed contact portions 54. A plurality of wiring patterns 55 extending in electrical contact with the fixed contact portion 54 and a connecting lead portion 56 for electrically connecting the fixed contact portion 54 and the wiring pattern 55 to the outside are provided. Part 56
Are arranged in parallel at the end 51c of the flexible insulating substrate 51.

The conductive pattern P1 is made of a conductive material in which Ag powder (silver powder) is dispersed in a polyester resin.
The g powder plays a role of imparting conductivity to the conductive pattern. The conductive pattern P1 is provided with excellent conductivity due to the good conductivity of Ag powder, but a migration phenomenon due to Ag powder may occur in high humidity.

In order to shield the conductive pattern P1 from humidity and prevent the migration phenomenon, the wiring pattern 55 of the conductive pattern P1 is covered with a resist film 57 made of an insulating material such as vinyl chloride, and the fixed contact portion 5 is formed.
4 and the connecting lead portion 56 are covered with a conductive coating 59 in which carbon powder is dispersed in a binder resin.

The conductive pattern P1 is formed by patterning a conductive ink in which Ag powder is dispersed in an organic solvent containing a polyester resin by a screen printing method and then drying it to volatilize the organic solvent. is there.

Further, the fixed contact portion 54 and the connecting lead portion 5
The method of forming the conductive coating 59 covering the conductive pattern P is
After the production of 1, the conductive ink in which carbon powder was dispersed in an organic solvent containing a binder resin was positioned by screen printing so as to match and overlap each pattern of the fixed contact portion 54 and the connecting lead portion 56. After being aligned and patterned, the organic solvent is volatilized by drying.

A movable contact portion (not shown) is attached to the flexible insulating substrate 51, and the movable contact portion is in a state capable of electrically contacting each fixed contact portion 54. Further, the end portion 51c of the flexible insulating substrate 51 on which the connecting lead portions 56 are arranged in parallel is inserted into the insertion opening of the connector member incorporated in the electronic device, and the connecting lead portion 5 is formed.
By electrically contacting the conductive coating 59 on 6 with the conductive portion provided inside the insertion port of the connector member, the conductive pattern P1 is electrically connected to other members of the electronic device.

[0008]

With the recent miniaturization of electronic devices, connector members have become smaller.
When the connector member becomes smaller, the insertion opening of the connector member also becomes narrower. Therefore, it is necessary to make the width dimension W1 of the end portion 51c of the flexible insulating substrate 51 inserted into the insertion opening narrower. In order to form the plurality of connecting lead portions 56 on the narrowed end portion 51c of the substrate 51, it is necessary to arrange the plurality of connecting lead portions 56 side by side at narrower intervals.

However, in the conventional method of covering the connecting lead portion 56 with the conductive coating 59 in order to prevent the migration phenomenon of the connecting lead portion 56, the pattern of the conductive coating 59 is formed on the connecting lead portion 56. Even if the pattern position of the conductive coating 59 is slightly deviated from the pattern position of the connecting lead portion 56 in the step of overlapping the pattern, the conductive coating 59 is adjacent to the connecting lead portion 56 to be covered. There is a risk that the connection lead portions 56 may be contacted with each other to cause a short circuit between the adjacent connection lead portions 56. Therefore, there is a problem that higher precision is required for the alignment for overlapping the pattern of the conductive coating 59 on the pattern of the connecting lead portion 56, and the alignment work becomes complicated.

The present invention can respond to downsizing of electronic equipment,
It is an object of the present invention to more easily provide a printed wiring board in which a migration phenomenon does not easily occur.

[0011]

A printed wiring board according to the present invention comprises an insulating substrate, a plurality of wiring patterns provided on the insulating substrate, and the wiring patterns connected to the insulating substrate. A plurality of connecting lead portions arranged in parallel, and the connecting lead portions are formed on the surface of the conductive particles by Au.
(Gold) is formed of a conductive material in which a conductive powder formed by forming a coating layer is dispersed in a first binder resin, and
The main feature is that the wiring pattern is formed of a conductive material in which Ag (silver) powder is dispersed in a second binder resin.

In such a printed wiring board, the connecting lead portions juxtaposed to the printed wiring board are inserted into the insertion opening of the connector member incorporated in the electronic device, and the conductive material provided inside the insertion opening of the connector member. By making contact with the portion, the wiring pattern plays a role of electrically contacting with other members of the electronic device through the conductive portion of the connector member.

The conductive material forming the connecting lead portion is a conductive powder formed by forming an Au coating layer on the surface of conductive particles.
The first binder resin plays a role of a conductive filler that imparts conductivity to the conductive material, and the first binder resin is formed on the surface of the conductive particles by Au.
It plays the role of binding the conductive powder formed by forming the coating layer.

In the conductive powder formed by forming the Au coating layer on the surface of the conductive particles, the Au coating layer corrodes (oxidizes) the conductive particles.
Since it has both the function of preventing electromigration and the migration resistance, the conductive material to which the conductivity is imparted by the conductive powder formed by forming the Au coating layer on the surface of the conductive particles has the corrosion resistance and the migration resistance. It has the feature of being excellent.

The connecting lead portion made of such a conductive material does not hinder the conductivity of itself, and it is not necessary to provide a conductive coating for preventing migration. In the case of the connecting lead portion not provided with the conductive coating, the step of forming the conductive coating can be omitted, and since the conductive coating does not short-circuit between the connecting lead portions, a plurality of connecting lead portions can be provided. It is possible to arrange them side by side in a narrow region at narrow intervals and insert them into a narrow insertion port of a small connector member. Therefore, a printed wiring board compatible with small electronic components can be manufactured by a simple process.

The conductive particles forming the connecting lead portion are
Specifically, it is Ni (nickel) particles. Ni particles are A
Since the adhesion to the u coating layer is good, the surface of the core of the Ni particles can be reliably coated with the Au coating layer.

In addition, the conductive particles forming the connecting lead portion are formed by forming a Ni coating layer on the surface of the core and further forming an Au coating layer on the Ni coating layer, so that conductive particles other than the Ni particles are formed. It can be used. In that case, if Cu (copper) particles are used as conductive particles other than Ni particles,
Since Cu particles have a relatively low specific resistance, it is possible to suppress an increase in the conduction resistance value of the connecting lead portion.

In the conductive material forming the connecting lead portion, the main component of the conductive filler is Au on the surface of the conductive particles.
The conductive powder formed with the coating layer may contain carbon or the like as long as the conductivity and migration resistance of the conductive powder are not impaired.

The conductive material forming the wiring pattern is Ag.
The powder plays a role of a conductive filler that imparts conductivity to the conductive material, and the second binder resin plays a role of binding inclusions such as Ag powder.

Since the wiring pattern made of such a conductive material is provided with excellent conductivity from Ag powder which is a good conductor, it is possible to suppress power consumption and heat generation due to the current flowing through the wiring pattern. .

The conductive material forming the wiring pattern may contain carbon as a main component of the conductive filler as long as it does not impair the good conductivity of Ag powder.

As described above, by selectively using the conductive material forming the connection lead portion and the conductive material forming the wiring pattern, the connection lead having migration resistance while maintaining excellent conductivity of the wiring pattern. The parts can be arranged side by side in a narrow region in a narrow space without being covered with the conductive coating, and can be inserted into the narrow insertion port of the small connector member.

In the printed wiring board of the present invention, since the insulating substrate is flexible, the insulating substrate can be deformed according to the allowable space and housed in a small electronic device.

In the printed wiring board of the present invention, the connecting lead portion is harder than the wiring pattern.

In such a printed wiring board, since the connecting lead portion is hard, even if the connecting lead portion is pressed by the conductive portion (metal contact) of the connector member, it may be scraped or deformed. As a result, the electrical connection between the connecting lead portion and the conductive portion of the connector member can be made reliable and stable.

Further, since the wiring pattern is softer than the connecting lead portion, it is easy to be integrated with the flexible insulating substrate and the flexibility of the insulating substrate is not impeded.

In the printed wiring board of the present invention, since the first binder resin is a thermosetting resin, even if the connecting lead portion is pressed by the conductive portion of the connector member at a high temperature, the connecting lead portion is It is difficult to be deformed, and the electrical connection between the connecting lead portion and the conductive portion can be made reliable and stable.

In the printed wiring board of the present invention, the insulating substrate is made of a polyester resin film, the first binder resin is a phenol resin or an epoxy resin, and the second binder resin is a polyester resin. Is.

Since the second binder resin of the wiring pattern is the same polyester resin as the insulating substrate, the wiring pattern has good adhesion to the insulating substrate. Further, since the connecting lead portion is made of phenol resin or epoxy resin, it has excellent heat resistance and wear resistance.

In the printed wiring board of the present invention, a contact pattern that is electrically connected to the wiring pattern is provided on the insulating substrate, and the contact pattern is made of the same material as either one of the connection lead portion and the wiring pattern.

In such a printed wiring board, the contact pattern and the connecting lead portion, or the contact pattern and the wiring pattern can be simultaneously formed by printing, so that an increase in the number of forming steps can be suppressed.

In the printed wiring board of the present invention, since the wiring pattern is covered with the protective film made of an insulating material,
It is possible to prevent the migration phenomenon of the wiring pattern by blocking the wiring pattern from the external environment such as humidity.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION The printed wiring board of the present invention is used for an operation panel of a small electronic device and the like.
As shown in FIG. 3, a conductive pattern P is formed on one surface 1e and the other surface 1f of the flexible insulating substrate (hereinafter, flexible insulating substrate) 1. 1 is a plan view of the flexible insulating substrate 1 viewed from the one surface 1e side, and FIG. 2 is a plan view of the flexible insulating substrate 1 viewed from the other surface 1f.

The flexible insulating substrate 1 is made of a polyester film and has a rectangular contact region 1a, a lead-out region 1b extending perpendicularly from the contact region 1a, and an end of the flexible insulating substrate 1 protruding from the lead-out region 1b. And an insertion area 1c to be inserted into an insertion opening of a connector member (not shown). The pull-out area 1b is provided with a narrow portion 1d, which is narrowed toward the insertion area 1c, on the insertion area 1c side.
Is a rectangular shape protruding while holding the width W of the narrow portion 1d.

In the contact region 1a of the flexible insulating substrate 1, the first through holes 2 are provided at a plurality of positions corresponding to the plurality of push buttons supported by the frame of the operation panel so as to be able to move up and down. In the lead-out area 1b of the flexible insulating substrate 1, the same number of second through-holes 3 as the first through-holes 2 provided in the contact area 1a are provided. In addition, these first and second through holes 2, 3
Is filled with silver paste (not shown).

As shown in FIG. 1, in the contact region 1a on the one surface 1e side of the flexible insulating substrate 1, a plurality of contact patterns (hereinafter, fixed contact portions) 4 of the conductive pattern P are provided as the plurality of push buttons. They are arranged at corresponding predetermined locations. As shown in FIG. 4, the fixed contact portion 4 includes a plurality of conductive powders 23 formed by forming an Au coating layer 22 on the surface of Ni particles 21 which are conductive particles, by using a thermosetting resin such as a phenol resin or an epoxy resin ( A first fixed contact portion 4a, which is made of a conductive material dispersed in a first binder resin) and is formed inside the first fixed contact portion 4a. Is composed of a substantially circular second fixed contact portion 4b in a non-contact state.

The electroconductive powder 23 is formed by the electroless plating method, and the Ni particles 21 serving as the base in the electroless plating solution are used.
And the Au coating layer 22 is displacement-plated on the surface of the core of the Ni particles 21 by applying chemical substitution and reduction action of metals.

Further, inside the first fixed contact portion 4a,
The first through holes 2 are arranged one by one. The second fixed contact portion 4b is the first fixed contact portion 4
It is formed so as to cover a part of the first through hole 2 inside a, and is in contact with the silver paste filled in the first through hole 2.

The wiring pattern 5 of the conductive pattern P is made of a plurality of Ag powders made of polyester resin (second binder resin).
The first fixed contact portion 4 is made of a conductive material dispersed therein.
The first wiring portion 5a is in electrical contact with a and the second wiring portion 5b is in electrical contact with the second fixed contact portion 4b.

The first wiring portion 5a is, as shown in FIG.
The flexible insulating substrate 1 is formed on one surface 1e thereof, and has a plurality of first contact areas 1a in the flexible insulating substrate 1.
The fixed contact portions 4a are connected to each other and extended to the lead-out region 1b of the flexible insulating substrate 1.

As shown in FIGS. 1 and 2, the second wiring portion 5b is formed on both the one surface 1e and the other surface 1f of the flexible insulating substrate 1, and is located on the other surface 1f side of the flexible insulating substrate 1. As shown in FIG. 2, a plurality of (fixed contact portions 4
The same number as the second wiring portions 5b are formed. In the contact region 1a of the flexible insulating substrate 1, one end of each second wiring portion 5b has a first through hole 2a.
The second wiring portion 5b is in electrical contact with the second fixed contact portion 4b through the silver paste by contacting the silver paste filled inside. Further, the second wiring portion 5b formed on the other surface 1f side of the flexible insulating substrate 1 is extended to the lead-out region 1b of the flexible insulating substrate 1 to form the second wiring portion 5b.
The other end of the wiring portion 5b is in contact with the silver paste filled in the second through hole 3.

As shown in FIG. 1, a plurality of (the same number as the fixed contact portions 4) second wiring portions 5b are formed on one surface 1e side of the flexible insulating substrate 1. In the lead-out area 1b on the one surface 1e side of the flexible insulating substrate 1, each second wiring portion 5b comes into contact with the silver paste filled in the second through hole 3 to thereby obtain the silver paste and the flexible insulating substrate 1. Other side 1f
It is in electrical contact with the second fixed contact portion 4b via the second wiring portion 5b formed on the side.

The wiring pattern 5 extends in the lead-out region 1b of the flexible insulating substrate 1 toward the insertion region 1c which is an end of the flexible insulating substrate 1.
The respective wiring patterns 5 are formed in a tapered shape, and the end portions of the wiring patterns 5 are juxtaposed in the width details 1d of the extraction region.

In the connecting lead portion 6 of the conductive pattern P, the above-mentioned plurality of conductive powders 23 are treated with heat such as phenol resin or epoxy resin which is harder than the polyester resin (second binder resin) of the wiring pattern 5. The conductive material is dispersed in a curable resin (first binder resin).
As shown in, the narrow portion 1d of the flexible insulating substrate 1 is connected to the end portion of each wiring pattern 5. In the insertion region 1c of the flexible insulating substrate 1, the connecting lead portions 6 have a substantially rectangular shape wider than the end portion of the wiring pattern 5, and are arranged at a narrow interval (about 0 mm) so as to fit within the width dimension W of the insertion region 1c. .5 mm) and arranged side by side.

The resist film 7, which serves as a protective film for the wiring pattern 5 of the conductive pattern P, is made of an insulating material such as vinyl chloride, and as shown in FIGS. 1 and 2, the flexible insulating substrate 1
The wiring pattern 5 is formed on the first surface 1e and the second surface 1f. A circular window 7a is provided at the position of the fixed contact portion 4 on the one surface 1e of the flexible insulating substrate 1, and the fixed contact portion 4 is exposed from the resist film 7. Further, the resist film 7 is not formed on the tip side of the insertion region 1c, and the connecting lead portion 6 is exposed from the resist film 7 (see FIG. 3).

Next, a method for manufacturing a printed wiring board of the present invention,
In particular, a method of forming the conductive pattern P will be described.

The step of forming the fixed contact portion 4 of the conductive pattern P and the step of forming the connecting lead portion 6 are performed at the same time, and the above-mentioned plurality of conductive powders 23 are dispersed in an organic solvent containing a phenol resin (or an epoxy resin). The conductive ink
After the pattern is formed on the flexible insulating substrate 1 by the screen printing method, the conductive ink is dried to volatilize the organic solvent.

In the step of forming the wiring pattern 5 of the conductive pattern P, the silver paste is filled in the first and second through holes 2 and 3 by the screen printing method and dried, and then the organic resin containing the polyester resin is used. A conductive ink in which Ag powder is dispersed in a solvent is pattern-formed on the flexible insulating substrate 1 by a screen printing method, and then the conductive ink is dried to volatilize the organic solvent.

The fixed contact portion 4 and the connecting lead portion 6
The forming step of the wiring pattern 5 and the forming step of the wiring pattern 5 may be performed later. First, the forming step of the fixed contact portion 4 and the forming step of the connecting lead portion 6 are simultaneously performed, and the wiring pattern 5 is formed later. Alternatively, the wiring pattern 5 may be formed first, and then the fixed contact portion 4 and the connecting lead portion 6 may be formed simultaneously.

After forming the conductive pattern P in this way,
The resist film 7 is formed on both surfaces of the flexible insulating substrate 1 by the screen printing method, and the production of the printed wiring board of the present invention is completed.

A method of assembling a substrate with a switch using the printed wiring board according to the present invention will be described. As shown in FIG. 3, a movable contact portion 8 in the shape of an inverted mortar and formed of a metal leaf spring opening to the flexible insulating substrate 1 side. Is placed on the first fixed contact portion 4a, and a holding sheet 9 made of a polyester film is placed.
Is adhered to one surface 1e of the flexible insulating substrate 1 with the movable contact portion 8 covered, and the movable contact portion 8 is fixed to the flexible insulating substrate 1 by the holding sheet 9. Note that FIG.
Then, the portion where the resist film 7 is provided is shown by hatching.

When the switch-equipped substrate thus assembled is incorporated into an electronic device, the insertion region 1c, which is the end of the flexible insulating substrate 1, is inserted into the insertion port of a connector member (not shown) incorporated in the electronic device. When inserted, the connecting lead portion 6 of the conductive pattern P comes into contact with the conductive portion serving as a power supply terminal provided inside the insertion port, so that the conductive portion of the connector member and the conductive pattern P come into electrical contact. There is. At this time, even when the connecting lead portion 6 is pressed by the conductive portion of the connector member, the phenol resin or the epoxy resin which is the material of the connecting lead portion 6 is hard, so that the connecting lead portion 6 is also The connection lead 6 is hard, and is hardly scraped or deformed. Also, because phenolic resins and epoxy resins are thermosetting,
Even if the electronic device is placed under high temperature, the connecting lead portion 6 does not deform.

When the printed wiring board is incorporated in an electronic device, the flexible insulating substrate 1 has a lead-out area 1b.
Is deformed into a bent state as necessary. At this time,
Since the polyester resin, which is the material of the wiring pattern 5, is soft, the wiring pattern 5 is a flexible insulating substrate 1.
Flexible insulating substrate 1 without impairing the flexibility of
It can be transformed together with. Moreover, since the polyester resin, which is the material of the wiring pattern 5, is the same material as the flexible insulating substrate 1, the wiring pattern 5 is hard to peel off from the flexible insulating substrate 1.

In an electronic device having such a printed wiring board built therein, the push button and the printed wiring board to which the movable contact portion 8 is attached constitute a push button switch device, and the push button switch device is formed through the conductive portion of the connector member. The connection lead portion 6 is connected to an external circuit, and a voltage is applied between the first and second fixed contact portions 4a and 4b during driving.

Then, when the push button on the operation panel of the electronic device is operated in this state and the movable contact portion 8 is pressed by the push button, the movable contact portion 8 is deformed against the spring property and the first contact portion is deformed. It contacts with the fixed contact part 4b of 2. At this time, the first and second fixed contact portions 4a and 4b electrically contact with each other via the movable contact portion 8, whereby the fixed contact portion 4 is turned on and a current flows through the conductive pattern P. The current flowing through the conductive pattern P is output as an ON signal from the connecting lead portion 6 via the conductive portion of the connector member. At this time, the main path of the current flowing through the conductive pattern P is the wiring pattern 5 extending from the fixed contact portion 4 to the connecting lead portion 6, and the wiring pattern 5 is excellent from Ag powder, which is a good conductor. Since the conductivity is imparted, it is possible to suppress power consumption and heat generation due to the current flowing through the conductive pattern P.

Although the fixed contact portion 4 and the connecting lead portion 6 of the conductive pattern P are made of the same conductive material in the above embodiment, the fixed contact portion 4 is made of the same conductive material as the wiring pattern 5. You may form.

At this time, the method of forming the conductive pattern P is as follows.
It has a step of simultaneously forming the fixed contact portion 4 and the wiring pattern 5, and a step of forming the connecting lead portion 6.

Further, in this case, in order to prevent the migration phenomenon of the fixed contact portion 4 due to silver, a conductive film such as a carbon material which covers the fixed contact portion 4 may be provided.

In the above-described embodiment, the conductive material of the wiring pattern 5 is made of Ag powder and polyester resin, but the conductive material is carbon unless the conductivity of the conductive material provided by Ag powder is impaired. Etc. may be contained.

The conductive material of the connecting lead portion 6 is composed of the conductive powder 23 and phenol resin or epoxy resin, but the conductivity and migration resistance of the conductive material provided by the conductive powder 23 are impaired. Unless otherwise specified, the conductive material may contain carbon or the like.

Further, in the above embodiment, the case where the conductive powder 23 is dispersed in the phenol resin or the epoxy resin has been described, but instead of the conductive powder 23, as shown in FIG. Ni coating layer 2 on the surface of the core
5, the Au coating layer 22 may be further formed thereon to disperse the conductive powder 26 made of the conductive particles 24 other than the Ni particles 21 in the phenol resin or the epoxy resin. When Cu particles are used as the conductive particles 24 other than the Ni particles, since the Cu particles have a relatively low specific resistance, it is possible to suppress an increase in the conduction resistance value of the connecting lead portion 6.

The electroconductive powder 26 is formed by electroless plating, and the electroconductive particles 2 serving as the base in the electroless plating solution are used.
4 is immersed, and the Ni coating layer 25 and the Au coating layer 22 are sequentially displacement plated on the conductive particles 24 by applying chemical substitution and reduction action of metals.

Next, in the above embodiment, the connecting lead portion 6 is used.
The migration resistance of the conductive material used for the above will be described. The migration resistance was measured using the device shown in FIG.

On the substrate 11 made of an insulating material, two strip-shaped patterns 12 (width 2 mm, length 40) made of a conductive material are provided.
mm) are formed in parallel at intervals of 1 mm, and one strip-shaped pattern 12 has first and second resistors 1 of 10 kΩ.
3, 14 are connected in series. Then, with the two strip-shaped patterns 12 covered with distilled water 15, a direct current voltage of 10 V is applied between the two strip-shaped patterns 12 via the first and second resistors 13 and 14, and the first striped pattern 12 is applied. The voltage value across the resistor 13 was measured.

The graph of FIG. 5 shows the changes over time in the measured voltage value across the first resistor 13. When the two strip-shaped patterns 12 made of a conductive material are brought into conduction by a migration phenomenon, a current flows through the first resistor 13 and the voltage value across the first resistor 13 to be measured rises.

When the two strip-shaped patterns 12 are formed by using a conductive material in which the same conductive powder 23 as the connecting leads 6 is dispersed in phenol resin, the measured voltage value is
Hardly rose. On the other hand, two strip-shaped patterns 1
When 2 was formed using a conductive material in which Ag powder was dispersed in phenol resin, the voltage value rapidly increased with time. From the above results, it can be seen that the conductive powder 23 has significantly better migration resistance than the Ag powder.

The two strip-shaped patterns 12 are formed of a conductive material or conductive powder 26 in which conductive powder 23 is dispersed in epoxy resin.
The voltage value measured hardly increased when the conductive material was dispersed using phenol resin or epoxy resin.

[0068]

In the printed wiring board of the present invention, the plurality of wiring patterns 5 are made of a conductive material containing Ag powder, and the connection lead portions 6 connected to the end portions of the wiring patterns 5 and arranged in parallel are provided. It is made of a conductive material containing the conductive powder 23 and the conductive powder 26.

In such a printed wiring board, by selectively using the conductive material forming the connecting lead portion 6 and the conductive material forming the wiring pattern 5, A of the wiring pattern 5 can be obtained.
While maintaining the excellent conductivity imparted by the g powder, the connecting lead portions 6 having migration resistance are juxtaposed in a narrow region at a narrow interval without being covered with a conductive coating, thereby providing a compact connector. It can be inserted into the narrow insertion opening of the member.

[Brief description of drawings]

FIG. 1 is a plan view of a printed wiring board of the present invention viewed from one surface side.

FIG. 2 is a plan view of the printed wiring board viewed from the other surface side.

FIG. 3 is an exploded perspective view illustrating assembly of a switch-equipped substrate using the printed wiring board.

FIG. 4 is a schematic sectional view showing conductive particles constituting a conductive material used for the printed wiring board.

FIG. 5 is a schematic cross-sectional view showing another embodiment of the conductive particles constituting the conductive material.

FIG. 6 is an explanatory diagram of an apparatus for measuring migration resistance of a conductive material.

FIG. 7 is a graph showing migration resistance of a conductive material used for a connecting lead portion provided on the printed wiring board.

FIG. 8 is a plan view of a conventional printed wiring board.

[Explanation of symbols] 1 Flexible insulating substrate 1a Contact area 1b drawer area 1c insertion area 1d narrow part 1e One side 1f other side 2 First through hole 3 Second through hole 4 Fixed contact part (contact pattern) 4a First fixed contact portion 4b Second fixed contact portion 5 wiring patterns 6 Lead for connection 7 Resist film (protective film) 7a window 8 movable contact 9 holding sheet 21 Ni particles 22 Au coating layer 23 Conductive powder 24 Conductive particles 25 Ni coating layer 26 Conductive powder

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/12 610 H05K 3/12 610B F term (reference) 4E351 AA02 BB01 BB31 BB38 CC11 DD05 DD06 DD19 DD52 DD55 EE03 EE11 EE15 EE16 GG09 GG12 5E317 AA04 AA07 BB12 BB13 BB14 BB15 CC22 GG09 GG11 GG14 5E343 AA02 AA16 BB12 BB23 BB24 BB25 BB44 BB72 BB75 AO BB75 BB07 AO BB10 BB10 BB07

Claims (9)

[Claims] 1. An insulating substrate, a plurality of wiring patterns provided on the insulating substrate, and a plurality of connecting lead portions which are respectively connected to the wiring patterns and arranged in parallel on the insulating substrate. And the connection lead portion is formed of a conductive material in which conductive powder obtained by forming an Au coating layer on the surface of conductive particles is dispersed in a first binder resin,
A printed wiring board, wherein the wiring pattern is formed of a conductive material in which Ag powder is dispersed in a second binder resin. 2. The printed wiring board according to claim 1, wherein the conductive particles are Ni particles. 3. The printed wiring board according to claim 1, wherein a Ni coating layer is provided between the surface of the conductive particles and the Au coating layer. 4. The printed wiring board according to claim 1, wherein the insulating substrate has flexibility. 5. The printed wiring board according to claim 4, wherein the connecting lead portion is harder than the wiring pattern. 6. The printed wiring board according to claim 5, wherein the first binder resin is a thermosetting resin. 7. The insulating substrate is made of a polyester resin film, the first binder resin is a phenol resin or an epoxy resin, and the second binder resin is a polyester resin. 6
The printed wiring board according to. 8. A contact pattern, which is electrically connected to the wiring pattern, is provided on the insulating substrate, and the contact pattern is made of the same material as either one of the connection lead portion and the wiring pattern. Claim 1 characterized by
The printed wiring board according to any one of items 1 to 7. 9. The wiring pattern is covered with a protective film made of an insulating material.
The printed wiring board according to any one of 1.